In the field of commercial printing, there is a rising demand to customize and to increase the quality of a printed material. As the methods of implementing this demand, there are techniques to control the glossiness of a printed material. As such techniques, a method of controlling the use amount of a glossiness adjustment material (Japanese Patent Laid-Open No. 2008-213271), a method of implementing a uniform glossiness by controlling the concentration degree of a dot arrangement (Japanese Patent Laid-Open No. 2010-120185), and a method of implementing a uniform glossiness by changing the number of printing scans for each color material (Japanese Patent Laid-Open No. 2012-035603) are known. In each of these techniques, it is necessary to perform glossiness control and to prevent image quality degradation of a color image.
According to the technique of Japanese Patent Laid-Open No. 2010-120185, although it is possible to control glossiness in a predetermined area of an image, the number of reproducible glossiness tones is limited to the number of dot arrangement types. According to the technique of Japanese Patent Laid-Open No. 2012-035603, the number of reproducible glossiness tones is limited to the number of scanning count types. Hence, according to these techniques, it is difficult to obtain a smooth glossiness change since the number of glossiness tones is small.
In contrast, according to the technique of Japanese Patent Laid-Open No. 2008-213271, the number of reproducible glossiness tones is determined by the use amount of a glossiness adjustment material, and smooth glossiness control is possible. However, a glossiness range (dynamic range) that is controllable by only the use amount of a glossiness adjustment material is not very wide. In this manner, it is difficult to obtain a smooth gradation reproduction of glossiness in a wide dynamic range by conventional glossiness control techniques.